Wrasses find Sand bed containers just fine. I had one in my qt and all the wrasses found it after a couple of hours. Once they know where it is they will continue to go back to that spot for bedtime or when they are frightened. With that being said, who wants a container in their display...
I would add some sand but as long as the wrasses can fully cover their body they will be ok. The problem is they throw sand around and with one inch only you will get thin in spots. Also, they don't usually dive straight down, they go at an angle so they can shovel themselves in, so they shouldn't damage their nose really. Finer grain sand is what most go for with wrasses because the crushed coral doesn't look comfy
The trick to getting them to eat is finding a healthy specimen and throwing every frozen food you can get your hands on at him until one sticks. Good luck! I have another leopard coming tomorrow and will be doing the same thing.